1. Technical Field
The present disclosure relates to surgical fastener applying apparatus. More particularly, the present disclosure relates to a surgical fastener cartridge that includes a plurality of surgical fasteners and a mechanism for forming the surgical fasteners so as to apply different compressive forces to tissue depending on the location of the tissue with respect to the cartridge, and methods of manufacturing and using the same.
2. Background of the Related Art
Commercially available surgical fastening apparatus are well known in the art, some of which are specifically adapted for use in various surgical procedures including, but not limited to, end-to-end anastomosis, circular end-to-end anastomosis, open gastrointestinal anastomosis, endoscopic gastrointestinal anastomosis, and transverse anastomosis. U.S. Pat. Nos. 5,915,616; 6,202,914; 5,865,361; and 5,964,394 each describe one or more suitable apparatus which may be employed while performing one of these procedures.
In general, a surgical fastening apparatus will include an anvil that is approximated relative to a fastener cartridge during use. The anvil includes depressions that are aligned with, and/or are in registration with slots defined in the cartridge, through which the fasteners will emerge. To effectuate formation, the fasteners emerge from the cartridge and are driven against the anvil. The fastener cartridge typically has one or more rows of fasteners disposed alongside a channel that is configured to accommodate a knife, or other such cutting element, such that tissue can be simultaneously cut and joined together. Depending upon the particular surgical fastening apparatus, the rows of fasteners may be arranged in a linear or non-linear, e.g. circular, semi-circular, or otherwise arcuate configuration.
Various types of surgical fasteners are well known in the art, including but not limited to unitary fasteners and two-part fasteners. Unitary fasteners have a pre-formed configuration and a formed configuration. Unitary fasteners generally include a pair of legs adapted to penetrate tissue and connected by a backspan from which they extend. In use, subsequent to formation, certain types of the unitary fasteners have a “B” shaped configuration. Typically, the two-part fastener includes legs that are barbed and connected by a backspan which are engaged and locked into a separate retainer piece that is usually located in the anvil. In use, the two-part fastener is pressed into the tissue so that the barbs penetrate the tissue and emerge from the other side where they are then locked into the retainer piece. The retainers prevent the two-part fastener from dislodging from the tissue. The two-part fasteners are not intended to be unlocked or removable. They are generally made of a bioabsorbable material.
A common concern in each of these procedures is hemostasis, or the rate at which bleeding of the target tissue is stopped. It is commonly known that by increasing the amount of pressure applied to a wound, the flow of blood can be limited, thereby decreasing the time necessary to achieve hemostasis. To this end, conventional surgical fastening apparatus generally apply two or more rows of fasteners about the cut-line to compress the surrounding tissue in an effort to stop any bleeding and to join the cut tissue together. Each of the fasteners will generally apply a compressive force to the tissue sufficient to effectuate hemostasis, however, if too much pressure is applied, this can result in a needless reduction in blood flow to the tissue surrounding the cut-line. Accordingly, the joining of tissue together in this manner may result in an elevated level of necrosis, a slower rate of healing, and/or a greater convalescence.
Consequently, it would be advantageous to provide a surgical fastening apparatus capable of limiting the flow of blood in the tissue immediately adjacent the cut tissue to effectuate hemostasis and wound closure, while maximizing blood flow in the surrounding tissue to facilitate healing. Additionally, when tissue is clamped and compressed between the anvil and cartridge, some of the fluid of the tissue is squeezed out so the tissue is compressed further at the portions of the cartridge adjacent the cut-line and anvil than at the lateral edges it may also be desirable to cut and staple across tissue that varies in thickness. It would therefore be advantageous to provide staples which could better accommodate these resulting different tissue thicknesses.